This invention relates to a mining machine having a rotor arm cutting assembly and more particularly to an extendable and retractable rotor arm for a boring-type mining machine and a method for repairing an extendable and retractable rotor arm.
In boring-type mining machines as illustrated in U.S. Pat. No. 2,299,593 a pair of rotor cutter arms are mounted on a pair of parallel positioned drive shafts that extend forwardly from a gear box at the front of a mining machine. Rotation of the drive shafts rotates the rotor cutter arms to cut a pair of parallel bores in a seam of coal or mineral material to dislodge the material from a mine face. A conveyor mounted on the mining machine conveys the dislodged material rearwardly from the mine face for subsequent conveyance of the material from the mine. Also associated with the rotor cutter arms are cutter bars also mounted on the gear box above and below the rotor cutter arms. The cutter bars include orbitally movable chains that dislodge the cusps depending from the mine roof and upstanding from the mine floor formed by the boring action of the rotor cutter arms.
U.S. Pat. No. 2,937,859 discloses a boring-type mining machine that includes a rotor cutter arm having a base member and a cutter carrier member. The cutter carrier member fits over the base member to telescope relative to the base member. A piston cylinder assembly positioned in the base member is secured at one end to the base member and at the opposite end to the cutter carrier member. Actuation of the piston cylinder assembly shifts the cutter carrier member on the base member from a retracted position to an extended position.
A common form of extendable rotor arm for mining machines includes a rotor arm having an end portion, a rotor arm extension having an internal opening in which the end portion of the rotor arm is axially slidably received and nonrotatable, and a seal between an internal surface of the internal opening of the rotor arm extension and the rotor arm. The internal opening of the rotor arm extension is non-circular and an external portion of the end portion of the rotor arm is non-circular such that the rotor arm extension is axially slidable and nonrotatable relative to the sleeve and the end portion of the rotor arm. The end portion of the rotor arm typically includes a key arrangement removably secured thereto, the key arrangement defining at least part of the non-circular external portion.
The portion of the rotor arm in contact with the seal is typically a metal casting that is chrome plated to assist in the sealing function. During operation, the chrome plating is subject to wear. Repair of the chrome plating is a time consuming and difficult task. It is desirable to provide a sealing arrangement in an extendable rotor arm assembly that is relatively easy and quick to repair or replace.
Another problem with prior art extendable rotor arm assemblies is that the forces on the rotor arm extension cause the key arrangement to wear. It is desirable to provide a key arrangement that is relatively easy and quick to repair or replace.
The mining machine, extendable and retractable rotor arm, and method of repairing an extendable and retractable rotor arm according to the present invention permit the foregoing problems with prior art mining machines to be overcome.
According to one aspect of the present invention, an extendable rotor arm for a mining machine includes a rotor arm having an end portion, a sleeve removably secured on at least part of the end portion, a rotor arm extension having an internal opening in which the sleeve and the end portion of the rotor arm are axially slidably received and nonrotatable, and a seal between an internal surface of the internal opening of the rotor arm extension and the sleeve.
According to another aspect of the present invention, a mining machine having extendable rotor arms includes a body, two or more drive shafts extending from a forward end of the body, one or more drives for rotating the drive shafts, and one or more extendable rotor arms mounted on each of the drive shafts. Each rotor arm has an end portion, a sleeve removably secured on at least part of the end portion, a rotor arm extension having an internal opening in which the sleeve and the end portion of the rotor arm are axially slidably received and nonrotatable, and a seal between an internal surface of the internal opening of the rotor arm extension and the sleeve.
According to another aspect of the present invention, a method of repairing an extendable rotor arm for a mining machine is provided. According to the method, a rotor arm extension, the rotor arm extension having an internal opening, is removed from an operating position on a rotor arm in which an end portion of the rotor arm and at least part of a sleeve on the end portion of the rotor arm are disposed inside of the internal opening of the rotor arm extension. The sleeve on the end portion of the rotor arm is replaced with a new sleeve. The rotor arm extension is replaced in the operating position on the rotor arm.
According to yet another aspect of the present invention, a method of repairing an extendable rotor arm for a mining machine is provided. According to the method, a rotor arm extension, the rotor arm extension having an internal opening, is removed from an operating position on a rotor arm in which an end portion of the rotor arm and a key on the end portion of the rotor arm are disposed inside of the internal opening of the rotor arm extension and the key is disposed in a keyway in the rotor arm extension. The key is replaced with a new key. The rotor arm extension is replaced in the operating position on the rotor arm.